Examples of laser sources or methods of their use are disclosed in:                Stokes, L. F., M. Chodorow, and H. J. Shaw; “All-fiber stimulated Brillouin ring laser with submilliwatt pump threshold”; Optics Letters Vol 7 No 10 pp 509-511 (1982);        Smith, S. P., F. Zarinetchi, and S. Ezekiel; “Narrow-linewidth stimulated Brillouin fiber laser and applications”; Optics letters Vol 16 No 6 pp 393-395 (1991);        Geng, Jihong, et al; “Highly stable low-noise Brillouin fiber laser with ultranarrow spectral linewidth”; IEEE Photonics Technology Letters Vol 18 No 17 pp 1813-1815 (2006);        Lee, H., Chen, T., Li, J., Yang, K. Y., Jeon, S., Painter, O., and Vahala, K. J.; “Chemically etched ultrahigh-Q wedge-resonator on a silicon chip”; Nature Photonics Vol 6 pp 369-373 (2012);        Li, J., Lee, H., Chen, T., and Vahala, K. J.; “Characterization of a high coherence, Brillouin microcavity laser on silicon”; Optics Express Vol 20 pp 20170-20180 (2012);        Pant, Ravi, et al; “On-chip stimulated Brillouin scattering”; Optics Express Vol 19 No 9 pp 8285-8290 (2011);        Geng, J., Staines, S., and Jiang, S.; “Dual-frequency Brillouin fiber laser for optical generation of tunable low-noise radio frequency/microwave frequency”; Optics Letters Vol 33 pp 16-18 (2008);        Gross, M. C., Callahan, P. T., Clark, T. R., Novak, D., Waterhouse, R. B., and Dennis, M. L.; “Tunable millimeter-wave frequency synthesis up to 100 GHz by dual-wavelength Brillouin fiber laser”; Optics Express Vol 18 pp 13321-13330 (2010);        Callahan, P. T., Gross, M. C., and Dennis, M. L.; “Frequency-independent phase noise in a dual-wavelength Brillouin fiber laser”; IEEE J. Quantum Electronics Vol 47 pp 1142-1150 (2011);        J. Li, H. Lee, K. Vahala; “Microwave synthesizer using an on-chip Brillouin oscillator”; Nature Communications Vol 4 p 2097 (2013);        Li, J., Yi, X., Lee, H., Diddams, S. A., Vahala, K. J.; “Electro-optical frequency division and stable microwave synthesis”; Science Vol 345 Issue 6194 pp 309-313 (2014);        Liu, Jinmei, et al; “Optical generation of tunable microwave signal using cascaded Brillouin fiber lasers”; IEEE Photonics Technology Letters Vol 24 No 1 pp 22-24 (2012);        Wang, Gaomeng, et al; “Watt-level ultrahigh-optical signal-to-noise ratio single-longitudinal-mode tunable Brillouin fiber laser”; Optics Letters Vol 38 No 1 pp 19-21 (2013);        Drever, R., Hall, J. L., Kowalski, F., Hough, J., Ford, G., Munley, A., and Ward, H.; “Laser phase and frequency stabilization using an optical resonator”; Applied Physics B Vol 31 pp 97-105 (1983);        T. W. Hänsch and B. Couillaud; “Laser frequency stabilization by polarization spectroscopy of a reflecting reference cavity”; Optics Communications Vol 35 No 3 p 441 (1980);        Ferre-Pikal, E. S., Walls, F. L.; “Microwave regenerative frequency dividers with low phase noise”; IEEE Transactions on Ultrasonics, Ferro-electrics, and Frequency Control Vol 46 No 1 pp 216-219, (1999);        Fortier, T., Kirchner, M., Quinlan, F., Taylor, J., Bergquist, J., Rosenband, T., Lemke, N., Ludlow, A., Jiang, Y., Oates, C., et al; “Generation of ultrastable microwaves via optical frequency division”; Nature Photonics Vol 5 pp 425-429 (2011);        Swann, W. C., Baumann, E., Giorgetta, F. R., and Newbury, N. R.; “Microwave generation with low residual phase noise from a femtosecond fiber laser with an intracavity electro-optic modulator”; Optics Express Vol 19 pp 24387-24395 (2011);        H. Murata, A. Morimoto, T. Kobayashi, and S. Yamamoto; IEEE J. Sel. Top. Quantum Electron. 6, 1325 (2000);        A. J. Metcalf, V. Torres-Company, D. E. Leaird, and A. M. Weiner; “High-Power Broadly Tunable Electrooptic Frequency Comb Generator”; IEEE J. Sel. Top. Quantum Electronics Vol 19 p 3500306 (2013);        U.S. Pat. No. 9,450,673 entitled “Stabilized microwave-frequency source” issued Sep. 20, 2016 to Vahala, Diddams, Li, Yi, and Lee;        U.S. Pub. No. 2015/0236789 entitled “Dual-frequency optical source” published Aug. 20, 2015 in the names of Vahala and Li;        U.S. Pub. No. 2015/0311662 entitled “Stable microwave-frequency source based on cascaded Brillouin lasers” published Oct. 29, 2015 in the names of Li and Vahala; and        U.S. Pub. No. 2016/0254646 entitled “Optical frequency divider based on an electro-optical-modulator frequency comb” published Sep. 1, 2016 in the names of Li and Vahala.        
Each reference, patent, and publication listed above is incorporated by reference as if fully set forth herein.